The Beginner's Guide to Reading Food Labels in the UK

You pick up a product in the supermarket. The front says "high in protein" and "source of fibre" and has a picture of a sun-drenched field. The back has a table of numbers, a percentage column that means nothing to you, and an ingredient list in 6-point font that reads like a chemistry textbook.

Most people look at the front, shrug at the back, and put it in the trolley. The food industry is counting on this. The front of a package is advertising. The back is where the truth lives. Learning to read it takes about five minutes and changes how you shop forever.

The traffic light system

The UK uses a voluntary front-of-pack traffic light labelling system. It is the single most useful quick-reference tool on any product and it is worth understanding properly.

Each product shows colour-coded indicators for fat, saturated fat, sugar, and salt per serving and per 100g. Green means low. Amber means medium. Red means high.

The per-100g column is the one that matters for comparison. The per-serving column is useful for knowing what you are actually consuming, but serving sizes are set by the manufacturer and vary widely between brands. One brand's "serving" of cereal is 30g. Another's is 45g. Comparing their per-serving values is comparing different quantities. Per 100g is the level playing field.

Quick reference thresholds (per 100g):

Fat: Green below 3g, Red above 17.5g. Saturated fat: Green below 1.5g, Red above 5g. Sugar: Green below 5g, Red above 22.5g. Salt: Green below 0.3g, Red above 1.5g.

A product with all green lights is low in fat, saturated fat, sugar, and salt. A product with multiple red lights is high in at least one of these. Most products are a mix, and that is where your judgement comes in.

What the traffic lights do not tell you: Protein content, fibre content, vitamin and mineral levels, degree of processing, and allergen information. A product can be all-green on the traffic lights and still be nutritionally poor if it contains almost nothing of value (rice cakes, for example, are low in everything including useful nutrients). The traffic lights tell you what to worry about. They do not tell you what to seek out.

The nutrition table

The full nutrition table on the back of every UK food product provides more detail. Here is what each line means and what to look for.

Energy (kJ and kcal). How many calories the product provides. Useful for general awareness but not the most important number on the table. A pot of Greek yoghurt and a chocolate bar might have similar calories but vastly different nutritional profiles.

Fat and saturated fat. Total fat is not inherently bad. The type matters. Saturated fat (from butter, palm oil, coconut oil, fatty meat) is the one linked to increased LDL cholesterol. Unsaturated fat (from olive oil, nuts, avocados, oily fish) is protective. The table shows total fat and saturated fat but does not distinguish between types of unsaturated fat. A product with 15g total fat but only 2g saturated fat (like a handful of almonds) is completely different from a product with 15g total fat and 10g saturated fat (like a pastry).

Carbohydrate and sugars. The "of which sugars" line shows total sugar content, both naturally occurring and added. The label does not currently distinguish between them in the UK (though this may change in future). A pot of plain yoghurt shows sugar because lactose is a sugar. A pot of flavoured yoghurt shows more sugar because table sugar or fruit concentrate has been added. The total sugar number alone does not tell you how much was added versus naturally present. Ingredient list inspection is needed for that.

Fibre. The UK recommendation is 30g per day. Most adults achieve about 18g. When comparing products in the same category, choose higher fibre where possible. Good sources provide 6g or more per 100g. A source of fibre needs at least 3g per 100g.

Protein. Not shown on the traffic lights but critical for satiety, muscle maintenance, and numerous body functions. When comparing products, higher protein per 100g is generally preferable. A product claiming "high in protein" must contain at least 20% of its energy from protein.

Salt. Shown as salt (not sodium) in UK labelling. Adults should consume less than 6g per day. Many individual products contain 1-2g per serving, which means three meals plus snacks can easily exceed the limit without ever touching a salt shaker.

The ingredient list

Ingredients are listed in descending order by weight. The first ingredient is the one present in the largest quantity. This single rule tells you more about a product than the entire nutrition table in many cases.

If sugar (in any of its forms) is in the first three ingredients, the product is predominantly sugar. Sugar appears under many names: sucrose, glucose, fructose, glucose-fructose syrup, high-fructose corn syrup, dextrose, maltose, honey, agave, maple syrup, molasses, fruit juice concentrate, and rice syrup. They are all sugar. Some are marginally less refined than others, but your body processes them all into glucose.

Long ingredient lists generally indicate higher processing. A tin of chopped tomatoes has one ingredient: tomatoes. A tomato pasta sauce might have 15-20 ingredients including sugar, modified starch, flavourings, and various additives. Shorter is usually better, though not always (some products legitimately need multiple ingredients).

"Flavourings" is a catch-all term that can cover natural or artificial flavour compounds. "Natural flavourings" sounds better but is not necessarily healthier. It means the flavour was derived from a natural source, not that it is a whole food ingredient.

Watch for phosphate additives if you have kidney disease. Any ingredient containing "phos" (disodium phosphate, tricalcium phosphate, sodium hexametaphosphate) indicates added inorganic phosphorus with near-100% absorption. Our kidney disease guide explains why this matters.

Health claims on the front

UK food law regulates which health claims can be made on packaging. But the regulations permit claims that are technically true while being functionally misleading.

"High in protein" means at least 20% of energy comes from protein. This sounds impressive but 20% is not high by any absolute standard. A product with 10g protein per 100g and 200 calories per 100g qualifies. The claim tells you it has protein. It does not tell you whether the protein content is actually good relative to similar products.

"Source of fibre" means at least 3g per 100g. "High in fibre" means at least 6g per 100g. Both are legitimate claims, but 3g per 100g is modest and you would need to eat a significant quantity to meaningfully contribute to your 30g daily target.

"No added sugar" means no table sugar, honey, or syrup was added during manufacturing. It does not mean the product is low in sugar. A fruit juice labelled "no added sugar" can contain 10g of naturally occurring sugar per 100ml. A "no added sugar" cereal bar sweetened with date paste is still a sugar-dense product.

"Light" or "lite" means the product has at least 30% less of a specific nutrient (usually fat or sugar) than the standard version. But 30% less of a very high number can still be high. A "light" mayonnaise might have 30g fat per 100g compared to 75g in the regular version. It is lighter, but it is still predominantly fat.

"Natural" has no legal definition in UK food labelling. It means whatever the manufacturer wants it to mean.

The allergen information

UK law requires that the 14 major allergens are highlighted in the ingredient list (usually in bold). These are: celery, cereals containing gluten, crustaceans, eggs, fish, lupin, milk, molluscs, mustard, nuts, peanuts, sesame, soybeans, and sulphur dioxide/sulphites.

"May contain" warnings (for example, "may contain traces of nuts") are voluntary. They indicate that the product is made in a facility that also handles the allergen, and cross-contamination is possible. For people with severe allergies, "may contain" warnings should be taken seriously. For people with milder intolerances, the risk from trace cross-contamination is typically very low.

Why scanning is faster

Reading and interpreting all of this information, across every product, for every shop, while accounting for your specific health conditions, is a significant cognitive task. This is exactly what MyFoodFit automates.

A single barcode scan analyses the nutrition table, reads the ingredient list, checks for allergens against your profile, evaluates ultra-processing level, applies your condition-specific constraints, and produces a personalised score in seconds. All the label-reading knowledge in this article, applied instantly, for your specific situation.

You should still understand how labels work. It makes you a more informed consumer and helps you evaluate products that are not yet in our database. But for the weekly shop, scanning is the practical shortcut that makes personalised nutrition accessible without a degree in food science.

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This content is for information only and does not replace medical advice.